1. Field of the Invention
The present invention relates to a display device and an electronic apparatus, and in particular, it relates to the structure of a display device suitably mounted on a portable electronic apparatus.
2. Related Art
In general, an electro-optical device such as a liquid crystal display device or an electro-luminescent display device is used as a display device mounted on a portable electronic apparatus. In particular, a cellular phone has a compact liquid crystal display device mounted in a small casing thereof. In recent years, a cellular phone of a double-sided display type, having compact liquid crystal display devices mounted on the front and back of a thin displaying portion thereof, is commercially available on the market. Such a cellular phone has a pair of liquid crystal display devices accommodated in the displaying portion of the casing thereof so as to lie back to back and placed so as to be visible from both the front and back sides thereof.
Many liquid crystal display devices have a structure in which a backlight serving as an illuminator is disposed behind a liquid crystal panel. Although a reflective liquid crystal display device having no such a backlight is available, its application is limited since its display is invisible in dark places and at night. Although the liquid crystal display device equipped with a backlight has a drawback in thickness, with the recent advancements in higher definition and color display of a compact liquid crystal display device, most portable electronic apparatuses have them mounted thereon. In recent years, there has emerged a transflective liquid crystal display device equipped with a backlight and able to perform both transmissive display and reflective display.
Since a portable electronic apparatus such as the above-mentioned cellular phone has become more compact and thinner year by year, a thin liquid crystal display device is strongly desired in accordance with this trend. In order to meet this requirement, a thinner liquid crystal panel and a thinner backlight are under development.
Unfortunately, the above-mentioned known cellular phone of a double-sided display type has problems in that, since a pair of liquid crystal display devices must be accommodated in its casing so as to lie back to back, it is hard to make the casing thinner, and, even when each of the liquid crystal display devices is made thin, the casing is thicker and heavier than a normal portable phone of a single-sided display type.
One method for solving the above problems lies in that a single backlight is shared by the front and back liquid crystal display devices so as to illuminate a pair of front and back liquid crystal panels. Whereas, in a cellular phone of a double-sided display type, since the display areas of the front and back liquid crystal display devices are generally different from each other, when a single backlight is shared by them as mentioned above, the luminance distribution of a large main panel is affected by an illumination action of the backlight applied on a small sub-panel disposed behind the main panel, thereby causing a risk that a shadow of the sub-panel is reflected in a display image of the main panel and thus its display quality deteriorates.
With this background, the present invention has been made in order to solve the above problems. Accordingly, it is an object of the present invention to provide a display device which offers double-sided display and achieves a thin structure and which prevents deterioration in display quality of both front and back display units when an illuminator such as a backlight is shared by these display units.